Originally Posted by Ovenall
With this expansion, is all new content available from a brand-new game? Anyone know?

Yeah, the expansion adds one extra act of content, right after Act 4 of D3. It continues the story. And it adds 10 more levels. What this means is it will cause a redistribution of what level you get at which act. Plus extra abilities/runes for all the 5 existing classes for the 10 extra levels.